This invention relates to an apparatus for controlling the movement of a fabric-supporting carriage in a quilting machine.
It is known that in quilting machines which are capable of performing stitching lines along non-rectilinear paths, the fabric-supporting carriage is caused to move transversally to the advancement direction of the material to be quilted. In these conventional quilting machines, such movement is obtained by providing the fabric-bearing carriage, at the side thereof, with cams or worm screws cooperating therewith, suitable to impart to the fabric-supporting carriage a reciprocating movement, the amplitude and speed of which depend on the shape of the stitching which one desires to obtain. The fabric-supporting carriage and consequently the article to be stitched are movable along a line in a plane at right angle to the movement of the needles which carry out the stitching.
A principal drawback presented by the conventional machines of the above-mentioned type is in the limitation of the possible shapes of the stitching which can be obtained because the non-rectilinear stitchings are obtained as a result of the composition of the relative movements of the material to be quilted, and the translation movement of the fabric-supporting carriage. Such movements are both rectilinear and at right angles to each other; therefore, it is apparent that the stitching pattern can only be varied by changing the relative speed of the two movements mentioned above.
There are also known quilting machines in which the fabric-supporting carriage moves both transversely to the advancement direction of the material to be quilted and along directions substantially parallel to the advancement direction. Thus the fabric-supporting carriage is endowed with a movement referred to in art as "floating" movement with respect to the needles. This movement of the carriage is obtained by using extremely complicated devices, such as for instance worm screws driven by step-by-step motors which are in turn programmed by computers or magnetic punched tapes. The cost of these conventional quilting machines is consequently very high.